Bob Shaw(click on names to see more mathematical fiction
by the same author)

...

A self-described `unimportant mathematician' who works on guidance systems for a British weapons manufacturer discovers, just by playing around with the formulas, a way to cause the explosion of every nuclear bomb in the world. While his marriage dissolves and people around him die or are kidnapped, he races to use this knowledge for the benefit of mankind.

The fact that he is a mathematician is mentioned frequently, and words like `Schrödinger Equation', `Hermite Polynomial' and `Legendre Function' are tossed around. However, the math is not discussed in explicit detail but rather is just used as an explanation for the key plot device: his ability to `make neutrons dance'. Still, even if the math content is not very high, I think this was a rather engaging and thought provoking cold war thriller which might be of interest to some of you out there. Unfortunately, it does not appear to be in print at the moment, but many used copies are available (see links in next paragraph).